Aristo solid state contator failure

Hello everyone. In my last printing session I was using my Beseler 45 MX with Aristo D2 cold head that is connected to my timer by Aristo solid state contactor model 1200 where suddenly the lamp turned off. After that, when I hit focus or print on the timer when the regulator is connected, the lamp won't turn on. After trying couple of things, I found that the lamp is still working (confirmed by connecting it directly to an outlet) which makes me believe that the voltage regulator is the culprit here. I tried to disassemble it to see what is going on but found these weird nuts/weldings (not sure what to call it) and I'm not sure how to disassemble it.

So here're my questions:
1- What do you think happened there? I didn't smell anything at the time.
2- How can I disassemble the regulator?
3- What can replace the regulator to connect to RH Designs F Stop timer?

Are you sure it is not the timer which is faulty?

ic-racer said:

Are you sure it is not the timer which is faulty?

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Yes, the timer still operating and counts down fine. I also connected the regulator to a Gralab timer and same issue happened. The issue is that when I hit focus or print on the timer when the regulator is connected, the lamp won't turn on

amellice said:

1- What do you think happened there? I didn't smell anything at the time.

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Could be a number of things. Getting access to the internals and preferably a schematic would be a great help; without either, it's gambling more than anything.
I assume it's some kind of (fairly simple) triac circuit; in these, sometimes the triac fails, sometimes a driver/pulse generator, or it might be something as simple as a capacitor that has had its best time.

amellice said:

2- How can I disassemble the regulator?

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I dunno, but the thing you're pointing at with the ballpoint looks like a rivet to me. Since these require access to both sides of the plate metal to install them, I suspect they don't have to be removed in order to open up the device. I bet it's there to hold an internal mounting bracket in place or something like that. You sure it's not some kind of snap-fit enclosure?

amellice said:

What can replace the regulator to connect to RH Designs F Stop timer?

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Any ready-made solid state relay with a 110V trigger and input voltage rating and a power handling capacity that fits the enlarger (unlikely to be an issue with most solid state relays). I've never looked for them, but given the omnipresence of solid state relays these days, I'm sure there's some nicely boxed units around that can act as a snap-in replacement.

That particular rivet is called a “Pop Rivet” and it can be drilled out. It can be popped in a closed box without access to the inside.

Bill Burk said:

That particular rivet is called a “Pop Rivet” and it can be drilled out. It can be popped in a closed box without access to the inside.

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and it looks to me from the photo that the rubber feet are mounted in the same way. The pop rivets are often aluminium which is quite easy to drill out as Bill has said. Only the bit at the top has to be drilled. If the feet are pop riveted, maybe it's them which holds the case together. My choice for this situation is a non-solid state contactor (relay in my part of the world), but I was brought up in the pre-solid state era.

Bill Burk said:

It can be popped in a closed box without access to the inside.

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Alright, I'm sorry, I didn't know that. If that's how they closed the box, then that's...a pity.

Thank you all for the help. I'll drill them out and report back